We have begun a study to look for extra-hepatic sites of HAV replication during experimental infection. Marmosets and chimpanzees are inoculated orally with wild-type or cell culture-adapted (AGMK Pass 30) HM-175 HAV. At serial time points animals are anesthetized and specimens of blood, saliva, and stool are obtained. Biopsies are taken from buccal mucosa, tonsils, and liver. These specimens are being analyzed for the presence of HAV by cell culture, cDNA hybridization, and immunofluorescence. In addition, primary cell cultures have been established from biopsies of gingiva and skin from the chimpanzees. These cell cultures will be infected with HAV in vitro for use as genetically restricted targets. Peripheral blood lymphocytes are being obtained by leukopheresis from the animals at various time points during infection. Incubation of these lymphocytes with the autologous HAV-infected target cells may indicate whether cellular immunity plays a role in the clearance of HAV-infected cells. Liver biopsies from the animals will be stained with antisera to lymphocyte markers (OK T4, OK T8, etc.) to determine which cell populations are associated with clearance of HAV infected hepatocytes.